Cryogenic phase manipulation with an impedance matched granular aluminium transmission line

We present an impedance matched transmission line made from high kinetic inductance superconductor, granular aluminium (grAl). Using a hybrid normal metal-superconducting ground plane we demonstrate resilience to out of plane magnetic fields without introducing substantial ohmic losses. Furthermore, we demonstrate in situ tunability of the characteristic impedance for applications involving phase manipulation of a transmitted signal without compromising the impedance matching of the line. Our results are immediately applicable in the design of superconducting traveling wave parametric amplifiers and in the cryogenic circuitry used for superconducting qubit readout.